American Practical Navigator: An Epitome of Navigation & Nautical Astronomy ...

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U.S. Government Printing Office, 1931 - Nautical astronomy - 852 pages
 

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Page 40 - St.-Cu.) at the center of the group, but the thickness of the layer varies. At times the masses spread themselves out and assume the appearance of small waves or thin slightly curved plates. At the margin they form into finer flakes (resembling Ci.-Cu.).
Page 295 - Every circumference of a. circle, whether the circle be large or small, is supposed to be divided into 360 equal parts called degrees. Each degree is divided into 60 equal parts called minutes, and each minute into 60 equal parts called seconds.
Page 41 - Woolpack Clouds — Thick clouds of which the upper surface is dome-shaped and exhibits protuberances, while the base is horizontal. These clouds appear to be formed by a diurnal ascensional movement which is almost always observable. When the cloud is opposite the sun, the surfaces usually presented to the observer have a greater brilliance than the margins of the protuberances.
Page 6 - Sumner Line of Position, furnished ready to lay down upon the chart by means of tables of simultaneous hour angle and azimuth of celestial bodies of declination ranging from 27 N. to 27 S. of the celestial equator...
Page 15 - Fathoms which correspond with the depths marked are called marks; the intermediate fathoms are called deeps; the only fractions of a fathom used are a half and a quarter. A practice sometimes followed is to mark the hand-lead line in feet around the critical depths of the vessel by which it is to be used. Lead lines should be measured frequently while wet and the correctness of the marking verified. The distance from the leadsman's hand to the water edge should be ascertained in order that proper...
Page 119 - Sun increased by 12h; sidereal time is the hour angle of the First Point of Aries.
Page 126 - The last direction of the ray is that of a tangent to the curved path at the eye of the observer, and the difference of the direction of the ray before entering the atmosphere and this last direction constitutes the refraction.
Page 161 - ... made to preserve her position as nearly as possible until daylight; when nothing being in sight, she was kept on ENE under short sail, with heavy gales; at about 10 AM an altitude of the sun was observed, and the Chronometer time noted; but, having run so far without any observation, it was plain the Latitude by dead reckoning was liable to error, and could not be entirely relied on. "Using, however, this Latitude, in finding the Longitude by Chronometer, it was found to put the ship 15
Page 116 - Greenwich, gives the ephemerides of the sun and moon, the geocentric and heliocentric positions of the major planets, the sun's coordinates, and other fundamental astronomical data for equidistant intervals of Greenwich mean time ; Part II, Ephemeris for the meridian of Washington, gives the ephemerides of the fixed stars, sun, moon, and major planets for transit over the meridian of Washington, and Part III, Phenomena, contains predictions of phenomena to be observed with data for their computation.
Page 4 - There shall be a Hydrographic office attached to the Bureau of Navigation in the Navy Department, for the improvement of the means for navigating safely the vessels of the Navy and of the mercantile marine, by providing, under the authority of the Secretary of the Navy, accurate and cheap nautical charts, sailing directions, navigators, and manuals of instructions for the use of all vessels of the United States, and for the benefit and use of navigators generally.

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